Micromotion Gmbh

Craig Brainerd VanCleve

Gregory Treat Lanham

Charles Paul Stack

A single tube Coriolis flowmeter having a balance bar that enhances the flowmeter sensitivity to material flow. The balance bar's design lowers its second bending mode response to have a frequency that may be lower than the flow tube resonant drive frequency. The lowering of the second bending mode frequency of the balance bar enables the Coriolis response of the vibrating flow tube with material flow to extend force from the flow tube through a brace bar to the balance bar. These Coriolis forces induce Coriolis-like response vibrations in the balance bar because of the lowered second bending mode frequency of the balance bar. The Coriolis response of the flowmeter is enhanced since the Coriolis-like response of the balance bar is out of phase with and is additive to the Coriolis deflection of the flow tube.

Sensitivity enhancing balance bar

A single tube Coriolis flowmeter of enhanced flow sensitivity in which material flow induces Coriolis deflections in a flow tube and Coriolis-like deflections in a balance bar vibrationally coupled to the flow tube. Both the Coriolis deflections and the Coriolis-like deflections have a phase shift determined by material flow and are used co-adjuvantly to derive material flow information. The flowmeter achieves a constant flow sensitivity over a range of changes in material density by 1) varying the flow sensitivity in a first direction under control of the ratio between the drive mode vibration amplitude of the flow tube and the balance bar and 2) varying the flow sensitivity in an opposite direction under control of the ratio between the Coriolis deflection amplitude of the flow tube and the Coriolis-like deflection of the balance bar. The drive mode vibration amplitude ratio varies with changes in drive mode frequency caused by changes in material density. The amplitude ratio of the Coriolis defection and the Coriolis-like deflection changes with changes in the magnitude of the separation of the drive mode frequency and the second bending mode frequency to the balance bar density which, in turn, is caused by changes in material density.

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Lyons, CO, United States of America

Craig Brainerd VanCleve